1. Field of the Invention
The present invention relates to surge protectors, and in particular to surge protectors for network interface devices.
2. Technical Background
Telephone service is provided by a telephone company (“provider”) to a number of different customers of the provider, commonly referred to as “subscribers.” Each subscriber may purchase as many separate telephone lines as desired and equip his or her home or business with various types of telephone equipment. Subscribers are responsible for proper operation of the telephone equipment at their end, and the provider is responsible for proper operation of the telephone network up to the interface between the provider wiring and the subscriber wiring.
A telephone network interface device (“NID”) serves as the demarcation point between the provider wiring and the subscriber wiring. A NID serves the function of isolating the provider portion of the system (i.e., the provider wiring) from that of the respective subscribers. Such isolation is desirable for a number of important reasons, including segregating the responsibility for faults or malfunctions that may occur in the respective parts of the system.
In practice, NIDs are typically mounted to an exterior wall of a house or building. Conventional NIDs generally include a container or housing, the interior of which is divided into a provider portion and a subscriber portion. Provider wiring typically enters the NID and terminates in the provider portion. The subscriber wiring typically enters the NID and terminates in the subscriber portion. At least one interconnect apparatus is located between the two portions and generally operates to connect the subscriber wiring to the provider wiring.
The provider portion also typically contains protective devices such as surge protectors to protect equipment and users from excess voltages. Surge protectors operate by diverting voltage surges, also known as overvoltages, on a telecommunications line to ground. Such surge protectors utilize various types of protection elements to divert unacceptable levels of voltage to ground. A surge protector that utilizes a single protection element may not offer sufficient protection against a prolonged voltage surge. A surge protector utilizing more than one type of protection element can provide redundancy or improve the performance of the surge protector. What is needed is a low-cost surge protector for a NID that provides such redundancy, that has a fast response, and that is usable in a variety of presently deployed NIDs.